<html>
<head>
  <style>
    #colset { -moz-column-count: 3; }
    #a { height: 0;   }
    #x { height: 3px; }
    #b { height: 0;   }
    #c { height: 2px; }
    #d { height: 2px; }

    /* Following style is just for visualization -- doesn't affect assertion */
    #colset { -moz-column-gap: 0px; width: 18px; }
    div { width: 5px;         }
    #a  { background: purple; }
    #x  { background: orange; }
    #b  { background: blue;   }
    #c  { background: black;  }
    #d  { background: lime;   }
  </style>
  <script>
    function boom()
    {
      document.getElementById("a").style.height = "auto";
      document.getElementById("c").style.height = "0";
    }
  </script>
</head>
<body onload="boom()" id="colset"
  ><div id="a"><div id="x"></div></div
  ><div id="b"><div id="c"></div><div id="d"></div></div
></body>
</html>
